diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9b8cf8a3cf6..adcbd058c5e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2005-08-12  Paul Brook  <paul@codesourcery.com>
+
+	* config/arm/lib1funcs.asm: Error if __ARM_ARCH__ not set.
+
 2005-08-12  Andreas Krebbel  <krebbel1@de.ibm.com>
 
 	* config/s390/predicates.md (setmem_operand): New predicate.
diff --git a/gcc/config/arm/lib1funcs.asm b/gcc/config/arm/lib1funcs.asm
index 3c6c1fe047f..952eb562a92 100644
--- a/gcc/config/arm/lib1funcs.asm
+++ b/gcc/config/arm/lib1funcs.asm
@@ -87,6 +87,10 @@ Boston, MA 02110-1301, USA.  */
 # define __ARM_ARCH__ 6
 #endif
 
+#ifndef __ARM_ARCH__
+#error Unable to determine architecture.
+#endif
+
 /* How to return from a function call depends on the architecture variant.  */
 
 #if (__ARM_ARCH__ > 4) || defined(__ARM_ARCH_4T__)